Maybe the fraction of users who do that is small enough that China won't push them on it. Or (this would be relatively easy to check) they could just hide that option in settings when the device region is China.
Another factor to consider is that SMS and iMessage are rarely used in China due to SMS historically being more expensive than email/data over there.
That brings up another point. How important is iMessage in China? The iPhone’s market share in China is small and statistically when you’re using iMessage you would probably be sending a message to a none Apple device over unencrypted SMS.
Email is the least secure method of sending data and always has been.
I’ve never paid attention to it until now, but you can selectively disable iCloud backups for any of the built in apps and third party apps in settings.
That brings up another point. How important is iMessage in China? The iPhone’s market share in China is small and statistically when you’re using iMessage you would probably be sending a message to a none Apple device over unencrypted SMS.
Email is the least secure method of sending data and always has been.
Another factor to consider is that SMS and iMessage are rarely used in China due to SMS historically being more expensive than email/data over there.